Abstract: A calibration device, method and apparatus is provided for checking calibration of a breath alcohol measuring instrument. A silicon wafer with an anti-reflective silicon monoxide coating on both sides is used to attenuate the infrared radiation in the range of 3.35 to 3.80 microns wavelength in a manner to simulate the attenuation caused by a breath sample containing 0.10 BrAC. A comparison of the signal generated by the attenuation at a wavelength of approximately 3.48 microns is made to the baseline signal obtained before placing the calibration disk in the IR beam path and accurately simulates the breath sample. The related breath alcohol measuring method and apparatus provides for the positioning of the composite disk in the path between the infrared source and receiver. A computer compares the signals and performs the calibration check, as well as the actual BrAC analysis.

Abstract: A battery-operated portable breath tester is disclosed. The breath tester includes a housing which defines a sleeve for receiving a wand. The wand defines an internal sample chamber, with a lamp at one end for providing infrared energy and a detector at an opposite end for receiving the infrared energy after it has passed through the sample to be tested. The wand defines opening extending from the internal sample chamber to the outside of the wand. The wand has an external shape providing a snug fit within the sleeve. As the wand is moved within the sleeve, gas is purged from the wand. The wand is connected to the housing by means of an electrical coil. The housing encloses a digital voltmeter including a digital display for providing a test readout. The digital voltmeter includes an oscillator which is coupled through a frequency divider and a transistor switch to the lamp.

Abstract: A method and apparatus for determining the concentration of a predetermined energy absorbing compound in a breath sample even in the presence of other unknown energy absorbing compounds. Infrared energy of three wavelengths are passed through the collected sample. The first wavelength of infrared energy, 3.95 microns for example, is selected to be insensitive to absorption by both the predetermined energy absorbing compound such as ethanol and the unknown energy absorbing compounds such as acetone and water vapor. The second wavelength of infrared energy, 3.48 microns for example, is selected to be significantly absorbed by ethanol. The third wavelength of infrared energy, 3.39 microns for example, is selected to be significantly absorbed by acetone and water vapor.